Wolff, Matthias (2010) Galapagos does not show recent warming but increased seasonality. Galapagos Research, 67 . pp. 38-44.

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Abstract

Recent literature postulates that Galapagos follows global warming, with an increase in sea surface temperature (SST) and frequency and amplitude of El Niño events. However, pronounced La Niña conditions over the last decade gave rise to the question of whether the “ocean thermostat model”, according to which heating of the tropics may lead to an increase in the temperature gradient across the equatorial Pacific, enhancing upwelling and surface cooling, may better describe what has recently occurred in the Eastern Tropical Pacific (ETP). A 44-year time series of measurements of SST, air temperature and rainfall taken on the Galapagos island of Santa Cruz revealed that Galapagos monthly mean SSTs have shown no pronounced trend, while annual rainfall has increased. Mean warm and cool season temperatures have slightly increased and decreased respectively, thereby increasing seasonality. Galapagos SST data did not correlate linearly with annual rainfall, which suggests that the latter is not a reliable proxy for reconstructing past SST trajectories. When compared with those of several ETP sites, the Galapagos SST series best correlates with those of Puerto Chicama (coastal Peru, 8°S) and Cocos Island (5°N). The Puerto Chicama time series, the longest available (1925–2006), showed a negative SST trend. Annual deviations in Galapagos SST from the trend line lie between the Chicama and Cocos Island curves, and follow the El Niño signals of the Chicama series in 1983, 1987, 1992 and 1997 more closely than the Cocos series. The Humboldt Current system coupled with the El Niño Southern Oscillation may be the main driver of interannual and interdecadal changes in the Galapagos climate. Since upwelling within the Humboldt Current has increased during the last decade of extended La Niña conditions, it is no surprise that the Galapagos climate has shown the same signal.

Document Type: Article
Research affiliation: Theoretical Ecology and Modelling > Resource Management
Refereed: Yes
Open Access Journal?: No
Date Deposited: 01 Oct 2019 17:36
Last Modified: 01 Oct 2020 13:00
URI: http://cris.leibniz-zmt.de/id/eprint/3014

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